Regardless of the supplementation form of astaxanthin (free vs. esterified), the free form is the only form found in human
blood after supplementation with either esterified or unesterified nature-identical and natural astaxanthin
(Okada et al. 2008; Osterlie et al. 2000; Coral-Hinostroza et al. 2004). Furthermore, it has also been
reported from studies in humans, that the esterified form of astaxanthin has a lower bioavailability than the
unesterified free-form. Coral-Hinostroza et al. (2004) showed that esterified astaxanthin has a lower
bioavailability in humans.